The present invention is directed to inks, especially conductive inks, that is, for example, inks that possess the quality of permitting the transmission of electrical signals generated by electric field assisted acoustic ink jet printing processes and apparatuses with controlled jettability leading to low edge raggedness such as equal to or less than about three microns. The conductivity of a material is usually measured in terms of the reciprocal of resistivity, which is the capacity for electrical resistance. The conductivity values of the invention inks can be expressed as log (pico.mho/cm) and were measured under melt conditions of 150.degree. C. by placing an aluminum electrode in the molten ink and reading the resistivity output on a GenRad 1689 precision RLC Digibridge at a frequency of 1 K.Hz. More specifically, the present invention relates to inks with a melting point of between (throughout between about is similar to from about and includes all values and numbers in between those recited) about 60.degree. C. and about 150.degree. C., and preferably between about 70.degree. C. to about 90.degree. C., and which inks are especially useful for electric field assisted acoustic ink jet printing with enhanced jettability, and acoustic ink processes and apparatuses, reference, for example, U.S. Pat. No. 5,121,141, U.S. Pat. No. 5,111,220, U.S. Pat. No. 5,128,726, U.S. Pat. No. 5,371,531, the disclosures of which are totally incorporated herein by reference, including especially acoustic ink processes as illustrated in some of the aforementioned copending applications, such as an acoustic ink printer for printing images on a record medium. The inks of the present invention in embodiments thereof can be considered a phase-change ink, that is for example an ink that changes from a liquid state to solid state in a suitable period of time, for example from about 1 to about 100 milliseconds and preferably in less than about 10, such as from about 2 to about 7 milliseconds, and which ink contains (1) a phase-change color spreading azole compound with, for example, 2 to 4 nitrogen atoms in the cyclic ring and selected for example, from the group consisting of pyrazole, imidazole, triazole, and tetrazole compounds, and which compounds can fill or substantially fill or be contained in the pores of a substrate such as paper, and which compound has a melting point of about equal to, or lower than about 135.degree. C. and preferably between about 55.degree. C. to about 100.degree. C., and with a low acoustic loss value of equal to, or below about 100 dB/mm, (2) a viscosity modifying compound that can, for example, reduce the viscosity of the ink from, for example, about 12 to about 6 centipoise and which compound is selected from derivatives of pyrrole, indole, imidazoline and thiazole compounds with, for example, a boiling point of equal to, or higher than about 150.degree. C. (Centigrade), and more specifically, possessing a boiling point of from about 150.degree. C. to about 225.degree. C., and a melting point of between about 25.degree. C. to about 130.degree. C. and preferably between about 55.degree. C. to about 100.degree. C., and with a low acoustic loss, which enables a reduction, or minimization of energy consumption, and which acoustic loss is below, or about equal to 60 dB/mm, (3) a lightfastness component, such as a UV absorber, (4) a lightfastness antioxidant, (5) and a colorant, such as a dye, a pigment or mixtures thereof.
More specifically, the present invention is directed to nonaqueous, that is inks that contain no water, or substantially no water, phase-change acoustic ink compositions comprised of (1) a phase-change azole compound, such as a pyrazole, an imidazole, a triazole, a tetrazole, and the like, each with a melting point of, for example, between about 60.degree. C. to about 135.degree. C. and preferably from about 60.degree. C. to about 100.degree. C., and each with a low acoustic loss value of, for example, between about 25 to 80 dB/mm, (2) a viscosity modifying compound that can reduce, or change the viscosity of the ink and which compound is, for example, selected from derivatives of pyrrole, indole, imidazoline and thiazole compounds each with, for example, a boiling point of from about 150.degree. C. to about 225.degree. C., and a melting point of between about 25.degree. C. to about 130.degree. C. and preferably between about 60 to about 100.degree. C., and with an acoustic loss of between about 15 to about 60 dB/mm, (3) a lightfastness UV absorber, (4) a lightfastness antioxidant, (5) and a colorant, and wherein there can be generated with such inks excellent developed images on plain and coated papers with acceptable image permanence, excellent projection efficiency on transparencies without, for example, a post fusing step, and excellent crease resistance, and wherein the inks possess acceptable, and in embodiments superior lightfastness of, for example, between about 90 to about 100 percent and superior waterfastness between, for example, about 95 to about 100 percent. Moreover, in embodiments of the present invention there is enabled the elimination, or minimization of undesirable paper curl since water need not be present, and it is preferred that there be an absence of water. When water is not present in the inks, a dryer can be avoided thereby minimizing the cost of the acoustic ink jet apparatus and processes.